Hydraulic drive powder catapult



Dec. 27, 1955 B. MAzls 2,728,538

HYDRAULIC DRIVE POWDER CATAPULT Filed Sept. 25, 1953 4 Sheets-Sheet l y4 'x I II IE @I IISIII Ox I I|IIIII I E III Il IHII S I||Il| Il Il |I nl III| i{Ilh} j \I I l, |'IIII N u: MKII g5 f iIIIII I l l I@ III; L i Wr\ I kk N I w I I I 215 II' I||| II )5 IIII II I I I I ,1| IIIIIIIIILIIIQIVI 1N VEN TOR. ERNHRD MAZ/5 H Trae/VE Ys Dec. l27, 1955 B.MAzls 2,728,538

HYDRAULIC DRIVE POWDER CATAPULT Filed Sept. 23, 1955 4 Sheets-Sheet 2JNVENTOR. 55 MII/zo MHz/5 @dun-IJ.. 751@ Dec. 27, 1955 B. MAzlsHYDRAULIC DRIVE POWDER CATAPULT 4 Sheets-Sheet 5 Filed Sept. 23, 1955INVENTOR. BER/vwo' Maz 1.5

Dec. 27, 1955 B. MAzls HYDRAULIC DRIVE POWDER CATAPULT 4 Sheets-Sheet 4Filed sept. 25, 195s IN VEN TOR BY K /9 Trai? v5 ys United StatesPatent@ HYDRAULIC DRIVE POWDER CATAPULT Bernard Mazis, WoodburyTownship, Gloucester County, N. J.

Application September 23, 1953, Serial No. 382,016

3 Claims. (Cl. 244-63) (Granted under Title 35, U. S. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or'therefor.

This invention relates to a propulsion device and more particularly to ahydraulic-drive powder catapult system particularly useful in connectionwith launching an aircraft or object into space.

At present there are in use several types of launching devices, namely,the compressed-air hydraulic, compressed-air slotted-tube and the powderslotted-tube catapults. However, utilization of the aforementioneddevices result in certain disadvantages. The compressedair hydrauliccatapult requires large and heavy accumulators for storing oil and airunder very high pressures. Such catapult is further limited as to theacceleration rate, maximum speed and power that can be generated, and torelatively long time intervals between recharging or tiring, since toimprove any of the above limitations would necessitate a substantialincrease in the size, number and weight of pumps needed to improvecatapult operation. Undesirable operating features similar to those ofthe hydraulic catapult are produced by the compressed-air slotted-tubecatapult.

The powder slotted-tube catapult requires an extremely heavy frameenclosure built up around the tube to prevent it from opening under highpressure and heat. in addition, a long strip must be provided to sealthe slotted tube as the launching piston travels during a stroke. At thecompletion of a power stroke such sealing strip falls away from the slotcausing llames and smoke to shoot out from the tube, therebynecessitating a large cover over the catapult for protection. Rapidtiring cannot be accomplished without providing a complicated coolingsystem because the split-tube structure does not lend itself toinstallation of 'a simple cooling jacket about the entire tube.Maintenance and repair of the catalpult can be accomplished only afterextensive dismantling of the protective coverings.

it is an object of this invention to provide a catapult apparatus thatwill overcome the above-stated disadvantages.

Another object of the invention is to provide a compact mechanism ofrelatively simple construction capable of delivering sufficient energyto catapult an airplane or other object into space.

A further object is to provide in an internal-combustion cylinder meansfor supplying a cooling liquid to the interior of the cylinder betweencombustion periods for rapid cooling.

Still another object is to provide in a catapult system braking meansfor limiting the stroke of the launching piston,

These and other objects of the invention and the various features anddetails of construction and operation thereof are hereinafter more fullyset forth and described with reference to the accompanying drawings inwhich like numbers refer to like parts.

2,728,538 Patented Dec. 27, 1955 Fig. l is an elevation view in sectionof the hydraulic powder-catapult mechanism of the invention,

Fig. 2 is an enlarged elevational view in section of the packing glandof Fig. 1,

Fig. 3 is a cross-sectional view of the packing gland taken along line3-3 of Fig. 2,

Fig. 4 is an elevational view in section of the oatingtype packingincluded in the packing gland of Fig. 2,

Fig. 5 is a cross-sectional view of the floating-type packing takenalong line 5--5 of Fig. 4,

Fig. 6 is a plan-view of a portion of the braking systern employed withthe invention of Fig. 1, and

Fig. 7 is an elevational view of the braking system of Fig. 6.

As shown in Fig. l, the device according to the invention consists oftwo chambers 11 and 13 each having keyways (not shown), both suchchambers connected at one end to a U-shaped chamber or elbow 15.Connected to the open end of chamber 11 is a breech or powder chamber17. Utilization of powder explosives as a motivating force in a catapultis ideal since it is a simple and compact source of power. Forward ofbreech 17 in the interior of chamber 11 is a keyed breech piston 19,said pistonV adapted for reciprocating movement within the chamber inits keyway. Combustion of a charge in powder chamber 17 exerts apressure against piston 19 causing the piston to act upon a hydrauliclluid 21, such as a mixture of glycerine and water, contained inchambers 11, 15 and 13 between pistons 19 and 23. A keyed launchingpiston 23, is situated within the interior of chamber 13 near elbow 15and is adapted for reciprocating movement within said chamber. Suitablyconnected to a terminal (not shown) in piston 23 are towing cables 25,said cable being threaded through holes in the wall of elbow 15. Theother ends of cables 25 pass through a packing gland 27 to a launchingcarriage (see Fig. 6).

Packing gland 27 is affixed to the lower portion of elbow 15 andcontains self-collapsing packing 29 having thrust bearings 31 and 31 toenable said packing to revolve about cables 25 (see Figs. 2, 4 and 5).Gland 27 also contains baies or compartments 33 having air jets 3Sinterspaced around the circumference of said baffles and at the bottompoints of compartment 33 are drain ports 37. Tubing 38 is attached atone end to packing gland 27, below ports 37 and connected at the otherend to a suction pump 39, said pump being connected by tubing 40 to auid reservoir 41. Stop rings or pins 43 mounted on theinner surfaces ofchambers 11 and 13 are adapted to limit the movement of pistons 19 and23 to the battery and launching positions. A normally open switch 45 islocated at the stop position of launching piston 23, said switch beingclosed when piston 23 bears against stop ring 43. Located at the elbowend of chamber 11 is an automatic solenoidoperated ll valve 47. Saidvalve 47 is normally closed. When piston 19 is in its forward positionafter a charge has been tired, valve 47 opens starting pressure pump 55.A solenoid-operated bleed-and-overflow valve 49 is so positioned onchamber 11 that the breech piston must bear against breech stop 43before fluid can ow through it to reservoir 41. Valve 49 contains aheat-activated switch 51 which operates to cut off pressure pump 55.

ln operation, powder-,is burned in breech 17. The expanding gasesproduced as a result of thecombustion ot' the charge exert a highpressure against breech piston 19 which in turn acts against thehydraulic iluid 21 confined in chambers 11, 15 and 13. Such pressure istransmitted by the liquid to act on launching piston 23. As thelaunching piston 23 is urged to travel in chamber 13, towing cables 25connected to piston 23 move with said piston, thereby actuating alaunching carriage (shown schematically in Fig. 6). The travel oflaunching piston 23 can be stopped and retracted by a hydraulic brakeand retracting engine such as is presently used with the slotted-tubepowder catapult or by means to be hereinafter discussed in detail.Partial braking (not shown) can also be accomplished by lowering ametering rod into the elbow after launching piston 23'exceeds thelaunching point. During the firing cycle valves 47 and 49 remain closed,pump 5S is inoperative and switch 45 is opened.

Retraction is accomplished by pulling back on towing cables 25. Duringretraction fuel valve 47 is opened and pressure purnp 55 is started.Fluid lostfin the packing gland through seepage is replaced. Such lesttluid is collected in packing gland 27 and returned to lluid reservoir41 by means of suction pump 39, said pump being in continuous operation.Fluid 21 pumped under pressure from reservoir 41 into chamber 11 exertsa pressure against breech piston 19 urging said piston to move to breechstop 43. Pump 55 also replaces any fluid that is vaporized by heat inbreech tube 11 after tiring. Valve 49 can be opened at the start of theretraction cycle, but, to prevent hot gases in chamber 11 from enteringliuid reservoir 41 through overflow line 57, it is preferable to openvalve 49 by a switch (not shown) after piston 19 reaches stop 43. Whenchambers l1 and 15 are rellcd with duid, excess duid will enter valveZi9 and return to reservoir 41 for recirculation, thereby acting as acooling system.

Overflow fluid 21 entering valve i9 activates iloat Sti, which in turncloses switch S1. By suitable circuitry of standard design, switch Si isconnected to pressure pump 55 to stop said pump and close valve i7 whensaid switch 51 is closed. (it is to be noted that instead of lioat Si?closing switch 51 thereby stopping pump 55 and closing valve i7 whensaid lioat Sil is actuated, oat 5S can actuate a signal lamp (not shown)allowing the fluid to circulate till just prior to the succeedingcatapult action, thus providing a means for cooling chamber 11.) Whenlaunching piston 23 reaches stop 43 switch 4S electrically connected inseries with switch 51 is closed. When switches 45 and 51 are closed,this automatically activates solenoid valve 49 and closes said valve.Float compartment in valve 49 is then drained. After draining, thedevice is in condition to be retired.

Split ring 29 in the packing gland 27 shown in Pigs. 2, 4 and 5 is usedto prevent escape of the hydraulic liuid 21 from elbow 15. Said ringcircumscribes the towing cables and prevents leakage of tiuid into gland2?. The shape of the ring bore 39 is determined by the outer surface ofthe cables used. As indicated in Fig. 5, bore 30 is designed forwire-rope cables presently used in catapult installations, and isbroached as closely as possible to the outer circumference of cables 25.Round cables can be substituted for presently used cables or additionalstrands of wire-rope can be added to the present cables to round themout. in addition, extra layers of line strand can be wound coilwisearound the cables to effect a more easily scaled surface and reduce theamount of leakage.

The split-rings are similar in principle to commercial type of packingused on rotating and reciprocating shafts in the manner in which theyarc cut so that they will close inwardly toward the center as they wear,and in the principle that the pressure confined by such rings aids insealing. Since the pressure acting on the outer circumference of thering is the same as the pressure acting at the inside diameter or boreand since the area of the outer surface is greater than the area of theinner surface, the eiective force acting to hold the segments againstthe rope is equal to the diierence in areas multiplied by the pressure.

in the present installation, since the segments are rotating at fairlyhigh speeds, the rings are designed so that the resulting force issuiiicient to overcome the centrilugal force acting to throw them awayfrom the rope. Retaining bearings (not shown) with adjustablepositioning and tension means can be used to retain the segments. As thetowing cable is pulled during launching and retraction cycles, thepacking collapses about cable 25 to seal out any lluid. Thrust bearings31 and 31 provided with split ring packing 29 enable the packing torotateY when cable 25 is pulled through it. This rotation results fromthe spiral or screw shape of the rope. Bearing 31 receives the loadduring the launching and braking cycle while bearing 31 receives theload during the retraction cycle. Air jet cleaners 35 are operated toblast oli any fluid that -seeps into packing gland 27. Such liuid issucked out of the gland through ports 37 into line 38 and thence toreservoir 41 by suction pump 39.

The automatic bleed system, whereby the fluid is allowed to circulate inchamber 11, as hereinbefore mentioned, reduces the temperature of thechamber and thus acts as a cooling system to prevent overheating. Saidsystem also replaces tluid vaporized by the heat generated in theinterior of the chamber due to combustion in the breech chamber.

Braking of the catapult mechanism can be accomplishcd by apparatus asshown schematically in Figs. 6 and 7. Cylinders 11' and 13 and elbow 15are similar to cylinders 11 and 13 and elbow 15 respectively, exceptthat instead of cylinders 11 and 13 resting in parallel planes, cylinder13 is tilted downward at an angle to cylinder 11'. Fluid 63 similar toiiuid 21 is placed in the lower portion of launching cylinder 13' overthe length designated as braking run so that piston 23 contacts fluid 63just prior to the end of the power or launching run of said piston.Trapped air in the braking run section of cylinder 13 can be allowed toescape or can be utilized as a cushion in decelerating the travel ofpiston 23. Cable 2S extends beyond elbow 15 and is suitably drawn over aseries of pulleys 65 and terminated in a terminal block of shuttle 67.

In addition to braking the travel of launching piston 23 after th'epower run shuttle 67 and towing cables 25 must not only be stopped butsaid Shuttle and cables must be decelerated in such a way that they willproduce a drag on piston 23' to maintain cables 25' taut. Attached tothe sides of shuttle 67 are cam-shaped elements 69. Said shuttle isadapted for reciprocating movement between guide rails 71 mounted belowthe deck plate of the flight deck or other launching surface. Disposedon the outer sides of guide rails 71 throughout the braking run are aseries of hydraulic cylinders 73. Said cylinders have a piston 75 thehead of said piston bearing against a lluid 77. Pivotally attached tothe end of piston rod 79 is a friction rail S1. The other end of rail 31is stationary but pivotable about a pin 83. As shuttle 67 travelsthrough the braking run section along guide rails 71, cam surfaces 69bear successively against friction rails Si urging piston 75 againstfluid 77 thereby compressing said uid. Such action produces a reactionagainst pistons 75 thereby applying a force through piston rods 79 andfriction brakes 81 against cam surfaces 69 retarding the forward motionot shuttle 67 until the shuttle speed is reduced to zero. This method offriction braking produces the desired results of decelerating shuttle 67and maintaining cables Z5 taut during the braking cycle.

From the above teachings it is seen that the present device does awaywith the heavy outer framework required for the slotted-tube typecatapult. No cooling system is required except a simple one for thebreech chamber. The simplicity of the present structure greatly rreduces the possibility ot any major mechanical failure and eliminatesthe necessity of considerable disassembly. By varying the ratios of thecross-sectional areas of the chambers, the power and speed ratiosbetween what the powder produces and what is required for launching anairplane or object can be varied. Said device can also make possiblemore uniform speed and acceleration, regardless of the variations inpower produced by the powder or of the varying weights of the objects tobe catapulted by the use of check and metering valves.

While a particular embodiment of the invention has been shown anddescribed herein, it is not intended that the invention be limited tosuch disclosure, but that changes and modiication can be made andincorporated within the scope of the claims. For example, in commercialadaptations of the invention, connecting rods can be attached to thepistons in place of the towing cables and each of the cylinders can bedesigned, with a head or combustion chamber for use with steam orgasoline in lieu of powder to produce a twin-cylinder pump or compressorwith continuous pressure or suction, or to produce a side-by-side ratherthan an opposed cylinder type reciprocating engine.

What is claimed:

1. In combination, a U-tube having each of its ends extendinghorizontally and in the same vertical plane, an explosion chamber in oneend, a piston next to, and adapted to be moved by an explosion in saidchamber, a second piston in the other end, liquid between the pistonsand tractive means extending from the second piston, through the liquidand through the walls of the U-tube comprising a wire-rope cable, apacking gland where said cable leaves the U-tube, and air jets in thepacking gland to blast oi'r the cable liquid that has escaped thepacking.

2. In combination, a U-tube having one of its ends extendinghorizontally, the other end of said tube extending at an angle to saidrst end, an explosion chamber in the horizontal end, a piston next to,and adapted to be moved by an explosion in said chamber, a second pistonin the other end, liquid between the pistons and tractive meansextending from the second piston through the liquid and through thewalls of the U-tube comprising a wire rope-cable, a packing gland wheresaid cable leaves the U-tube, air jets in the gland to blast off thecable liquid that has escaped the packing.

3. In combination with a cylindrical tube having a piston adapted forreciprocating motion therein, liquid means for exerting a pressure onsaid piston, and tractive means extending from said piston through theliquid and through the wall of said tube comprising a wire-rope cable, apacking gland where said cable leaves the tube, air jets in the gland toblast olf the cable liquid that escapes the packing.

References Cited in the tile of this patent UNITED STATES PATENTS525,434 Walker Sept. 4, 1894 816,643 Chiles Apr. 3, 1906 1,016,603 BakerFeb. 6, 1912 1,225,702 Davol May 8, 1917 2,289,766 Fieux July 14, 19422,373,972 Moreno Apr. 17, 1945 2,489,315 Paulus Nov. 29, 1949

